Apparatus for the drawing of tubular articles



G. DELPECH Jan. 17, 1933.

APPARATUS FOR THE DRAWING OF TUBULAR ARTICLES Filed March 12, 1931 RM o s ru w m M v m Ww T Patented Jan. 17, 1933 UNITED STATES ena-ron hmm or manas, nmen, assrexon. ro nu socnt'rfl "emmm armes," or runs, FRANCE, A conrona'rro o' :me:

PATENT OFFICE APPARATUS POR THE DBAWING OI' TUBULAB Anneme Application filed l'arch 12, 1931, Serial Io. mut and in !hace Ircl 28, "1030.

of the mandrel and die must be unchangeable. Now the mandrel cannot be fixed directly to the die since the production of a tube requres an annular space between the die and the mandrel. It is therefore necessary to extend the latter towards the interier of the vessel in order to carry well back its point f 2 of fixation thei-eto. e mandrel in question then traverses obligatorily, at the" time of the drawing, all or part of'the molten mass. u

silica, this neeessity does not involve any dificulties when the drawing vessel is at the same time the melting furnaoe and when the chrge to be melted is constituted by silica in powder or in It suflices to constitute this mandrel of a refractory material,

indeformble and without action on the silica being melted, andto fix the mandrel andthe to the furnaee before melting, thereafter .to charge the furnaee and lastly to draw .when fusion is complete;

But I have aseertained that die-drawing gave better results when, instead of starting from a ulverulent primary material, a start was mase from opaque or transparent silcia 49 'already melted in a preceding operation' and reeenting itself either in the form of a tubul r i'got, or in the form of a pounded block. In these conditions, as the forces exerted on the mandrel by the charge are not uniformly distributed, it is impoible to avoid deviations of the mandrel in the course of the melting operation.

My -esent invention has for object a method of drawin allowing of starting from a mass of any kin even not perforated, and

to weight the whole. This tube 12 psses at the centre of the aperture 17 in the plate ne ensuring in a sure manner among other advantages the fixity of the mandrel in relation to the die at the time of drawing.

The method consists in utilizing in combination with a melting furnace having a die, a mandrel arranged in such a way as to be able to move along its own axis and to through the molten material and to'become centered, in relation to the die, in the desired position in which it is immobilized.

This mandrel is tubular in order to allow the passage of air as a result of the natural draught* which is established in the interier of the latter, in such a way as to avoid soiling of the drawn product by the products of reduction of the material subjected to the drawing operation.

My invention relates likewise to methods of dsplacement, fixation and line-checking of the mandrel. ro

The accompanying drawing represents by: way ofexample'a view in vertical section of a.

form of Construction of a group, fu'maoe, In the particular case of the drawing of die, mandrel, in accordance with the invention. e e

I For the facility of the drawing it will be supposed that ths furnaee is cylindrical and that its axis 'is vertical.

The crucible 1 of a furnaee, heated in any I suitable manner (not represented) and suit-- ably heat insulated in a casing, is fixed rigidly above the hole in a base plate 2, by means of a plate 3 and clamping columns 4. These columns 4 are extended upwards and support anotherthree plates 5, 6, 7.

In the internally serew-threaded boss of the plate 5, there is engaged a tubulr part 8 externally screw-threaded, provided at its circunference with Operating handles 9 and comprising at its upper part a sphericl cavity 10, in which there entes the lower part of a member 11. This member 11 iorming a ball joint is extended upwards by. a tube 12 and downwards by a looking sleeve 13 ..intended to support by looking screws 28 the v carbon tube 14 forming the mandreL' The tube 12 carries also a heavy mass 16 intended lifted in such a way as to' ree the upper 6 and at its upper extremity terminates in a ponter 15.

The plate 7 comprises at its centre a hole 18. Upon its upper face rests a plate 19 carryng a pointer 20.

The carbon tube 14 is provided at its lower part with a fixed collar 21 which constitutes the active portion of the mandrel, that which shapes the interior of the tube in the course of drawing. It is provided moreover with a conical point 22, the tail of which is engaged with slight tightness, in the bore of the tube 14 at the extremity of the latter.

The crucible 1 narrowed down at its lower part 23 is` machined at 25 to receive without appreciable slack the ring 24 formin a die, in order to shape the exterior of t e tube during the drawing. In this die 24 is likewise engaged a member 26 formed with an axial hole and ressed against the lower face of the base 2 by ocking clamps 27. The whole of the members 26 and 24 forms in the crucible a conical bottom.

The plate 6 carries three long screws 30 which allow 'at will of fixing the tube 12 in the osition which it occu ies in the vicinity of t e center of the hole 1 Lastly the tube 14 comprises, at approximately of its part engaged in the furnace, a hole 31.

The operation is the following: v

One 'commences b screwing down the seat 8 in the plate 5. laving thereafter withdrawn the plate 19, the grou 12, 13, 14 is opening of the furnace. The prmary material is then introduced into the furnace. Two cases can present themselves' (1) If the primary material is in the form of a tubular ingot, the group 12, 13, 14 is allowed to come back to the position representcd in the drawing, passing through thehole in the ingot. Then the screws 30 are undone in order not tointerfere with the deviations of the mandrel and the heating can then be commenced. (2) 'If the primary material is a solid block, the oup 12, 13 14 is left in the raised position, t e tube 12 being clamped by the screws 13, and the heating is commenced.

When the tem rature approaches that which is suitable ih r the drawing operation, the rimary material softens and collects in the ottom of the furnace. In the first case (tubular ingot), it surrounds the mandrel. In the second case (solid block), this instant is chosen to undo the screws 30, in such a way as to free the roup 12, 13, 14 and to allow it to descend s owly like a unch under the efl'ect of its weight, throug the. soft mass. This descent requires for example one minute. Care will be taken to unscrew sufliciently the screws 30 in-order that, atthe end of the stroke, the point 22 slidin r on the conical bottom may center itself per ectly in the axial hole of the member 26, without being troubled in its movement, whatever may have been the deformations of the tube 14 in the course of the heating.

After a short time the temperature suitable for the drawing operation is attained. The members 8 forming the seat is then unsc'ewed until it is brought in contact with the ball 11, which has for eflect to maintain v without that position varying the least in the world. It sulfices then to continue the heating for a little while still in order that the molten material commencing to flow in the interval between the mandrel and the die,

it may be possible to seize it, to draw it at 'the desired speed, for example by the means rovided in the French Patent No. 629,453 led in the same name on the 4th`May 1926.

In order to faciltate the beginning of the flow of the molten material in the interval between the mandrel and the die, the plate 19 and the index 15 are removed, and there is 'engaged from the top in the group 12, 13, 14

a rod of carbon for example, by means of which pressure is exerted upon the tail of the cone 22 which thus passes out of the tube 14.

It is pointed out that the mandrel formed I by the group 12, 13, 14 is hollow and that there is established in the interior of themandrel at the moment of the drawing operatin a natural draught. This arrangement has %een recognized as indispensable. It has been ascertained in fact, that when it is not realized the interier of the drawn tube is soiled by the products of reduction which becomes condensed therein. In the case of silica, there is found a deposit of a very hard brown substance. This substance which answers to the formula SiO is derived from;

the partial reduction of the silica by the carbon. It suflices to ensure the passage of air b natural draught in the intcrior of the man rel in order to obviate these deposits.

It is preferable but not indis ensable to reset the pointer 15 in place in or er that the draught may be eficcted through the hole 31 into the furnace itself, that is in the hot zone. In fact, if the draught is allowed to take place by the tube 12, the vapours of silica 'condense against the wall of the latter and block it Very rapidly, which may cause trouble for subsequent Operations, but not prevent the druught which would then take place through the hole 31.

llC

names It is evident that all that has been said agplies to the case where, with a view to o taining certain complicated sections (tube with 2, 3 or 4 holes) it has been necessary to arrange in the die not one only but several nandrels.

It is likewise possible to utilize the axial displacement of the mandrel with a view to bottom to said crucible,

i which the varying the sectional area of the drawn product. This is a possibility of adjustment which constitutes an accessory advantage of the method.

Lastly, if for convenience of the description, all which ,precedes relates to molten silica, it must be understood that this is only b way of example and that the proces s a lutely general. It is applicable to the drawing 'of any mass, plastic' or rendered plastic by a physical agent such as a rise of temperature.

What I claim is: V a

1. An apparatus for drawing tubular articles of the type described, which comprises in combination, a crucible having an opening at its lower end, a hollow mandrel movably supported with respect to said crucible so as to extend thereinto and adapted to cooperate with said opening so as to form therewith an. annular passageway, a detachable bottom for said crucible adapted to obturate said opening and to cooperate with the lower end of said mandrel for accurately positioning the latter, means for' removably fastening said and adj ustable means for fixing said mandrel with'respect to said crucible, whereby the mandrel can be accurately positioned by means of the removable bottom, then securely fixed in that position with respect to said crucible, after which the detachable bottom is removed.

2. An a paratus according to' claim 1 in ollow mandrel is adapted to have its inside placed in communication withthe atmospbere t at least two points located at different lerels, so as to create a natural draught.

3. An apparatus for drawing tubular articles of the type described, which comprises in combination, a crucible having a circular opening at its lower end, a hollow mandrel movably supported with respect to said crucible so as to extend thereinto and adapted to cooperate with said opening so as to form therewith an annular passageway, a conical point at the lower end of said mandrel, a detachable bottom for said crucible adapted i to obturate said opening, the inside of said bottom having a conical shape for guiding the lower end of said mandrel and accurately centering it, means for removably fastening said bottom to said' crucible, and adjustable means for fixing said mandrel with respect to said crucible, whereby the mandrel can be accurately center'ed by means of the conical `removable bottom, then securely fixed in postherewith an annular passageway, a removable point of conical shape adapted to be fitted in the lower end of said mandrel, a detachable conical bottom for said crucible adapted to obturate said opening, said detachable bottom being provided with a central hole for receivin said removable point and thereby accurate y center in said man drel withrespect to said opening, means for removably fastening said bottom to said crucible, and adjustable means for securely fixing said mandrel with respect to said crucible, whereby the mandrel can be accurately centered by means of the removable bottom, then securely fixed in that position with respect to the crucible, after which the detachable bottom is removed.

5. An apparatus for drawing tubular articles of prises in combinaton, a crucible having a circular opening at its lower end, a tubular mandrel movably supported with respect to said crucible so as to eitend thereinto and ad. ted to cooperate with said opening so as to orm therewith an annular passa eway, said mandrel being provided with a ole for connecting its inside'with the inside of'the crucible above the level a removable point of conical shape ada te to be fitted in the lower end of sad man a detachable' conical bottom for said crucible adapted to obturate said o ning, said detachable bottom being rovi ed wthacentral hole'for receiving sa removable point and thereby accurate y centering said mandrel with respect to said crucible, means for re-- movably' fastening cible, and ad'usta le means for securely fixing said man el with respect to said crucible, whereby the mandrel can be accurately centered with respect to said opening by means of the detachable bottom, then securely fixed in that position, after which the detachable bottom is removed. a

6. An apparatus for drawing tubular articles of the type described, comprising in combination, a crucible' having .a circular openn extendng into said crucible ada ted to cooperate with said opening so as to orm therewith an annular pamageway, means for movabl supporting said mandrel with respect to sai crucible, whereby said mandrel is allowed sli ht displacements in all directions, a detacha le bottom for said crucible adapted to obturate 'said opening and to cooperate of the melted material therein said bottom to said cruat its lower end, a tubular mandrel with the lower end of said mandrel for accurately centering the letter, means for removably fastenin said bottom to said crucible, means for c ecking the `position of the mandrel with respectto the crucible in the centered osition, and adjustable means for securely xng said mandrel with respect to said crucible, whereby the mandrel can be accurately positioned with respect to the crucble by means of the removable bottom, then securely fixed in that position, after which the detachable bottom is removed;

In testmony whereof I have signed my name to this specication.

GASTON DELPECH. 

